278 NOTE ON THE ELLIPTICITY OF MARS, ETC. [35 



From this it may be inferred that the orbit of the 1st satellite pre- 

 serves a constant inclination to a plane which is inclined less than 1' to 

 the plane of Mars' equator, and that the orbit of the 2nd satellite preserves 

 a constant inclination to a plane which is inclined about 1 to the plane 

 of the same equator. 



The ellipticity will also cause rapid motions in the apses of the orbits 

 of the satellites, particularly in that of the first ; and as this orbit appears 

 from Professor Hall's determination to have a sensible eccentricity, it will 

 be possible, by future observations, to determine the motion of the apse, 

 and therefore the ellipticity of the planet. If further observations shew 

 that the orbits of the satellites are sensibly inclined to their fixed planes, 

 the motion of their nodes will supply another means of determining the 

 ellipticity of the planet. 



